Patent GB-944142-A (GB)
Title: Clutch brake control means
IPC: D01H1/36
Filed: 1962-06-18
Abstract: 944,142. Gearing for starting and stopping machinery. SINGER CO. June 18, 1962 [June 23, 1961], No. 23425/62. Heading F2L. [Also in Division D1] The control means for a clutch brake unit is fed from a substantially constant pressure source through a conduit having a valve means and means for selectively metering the flow of fluid through the valve means. A roving machine 11 is driven through a clutch brake unit, from a substantially constant speed motor 20, and has a timing shaft 13 driving a position sensing device within a casing 102 to enable the roving machine to be stopped in predetermined or random positions. Compressed air from a conduit 74 is metered into a reservoir 76 through a needle valve 75 and, on opening of a solenoid controlled three way valve IV, passes to a clutch operating cylinder 59 to move a piston 55 against a spring 60, thereby axially moving a sleeve 42 bearing a shaft 30. The shaft 30 carries a disc 37 having a brake lining 39 engaged by the spring 60 against a brake surface 27, and a clutch lining 38 engaged with a clutch disc 23, on motor shaft 24, when the shaft 30 is moved axially by the piston 55. The volume of the reservoir 76 is such that on actuation of the valve IV the piston is initially moved sufficiently to disengage the brake and thereafter the metered flow through the valve 75 engages the clutch at a predetermined rate. Fast clutch release and predetermined brake engagement rate are provided by a second reservoir 86 and needle valve 87, open to atmosphere, connected to the cylinder 59 when the valve IV is de-energized. Fast clutch release and fast brake engagement are produced by a second normally closed solenoid valve 2V exhausting direct to atmosphere. A position sensing device, Fig. 4, to provide rapid stopping of the machine with the thread guides outwards on breakage of the thread or with a thread guides inwards when the cop is full, is driven from the timing shaft 13 by a toothed belt 116. A spindle 110 driven at the speed of the roving machine by the belt 116 has a brush contact 114 and carries a rotator 118 on which is pivoted a switch arm 120 urged inwards against centrifugal force by a spring 121; the spring strength being such that at normal speed centrifugal force holds the arm 120 clear of two fixed switch contacts 162, 163 and of a rotating timing finger 170. The timing finger 170 is driven at approximately one eightieth of the machine speed by a constant speed motor 130 through a gear train 144 . . . 148<SP>1</SP>, 142 carried on spindles 139, 149 in a rotatable cage 136, 137 having a torque arm 171, the normal torque of which is resisted by the springs of a pair of micro-switches 175, 176. Excess torque occurring on slowing down of the machine, and spindle 110, due to engagement of the finger 170 with the switch arm 120 is sufficient to actuate the switches 175, 176. The solenoid valves IV and 2V are energized by an electrical circuit, Fig. 7, controlled by switches S-1, providing normal starting and random position stopping at predetermined rates of acceleration and retardation and by switches S-2, S-3, respectively sensitive to thread breakage and full cop for rapid stopping in predetermined positions. The switch S-1 in circuit with a latching relay LR having contacts LRA, LRB, LRC is closed momentarily to close a holding relay R4, having contacts R4A, R4B, R4C and is thereafter closed to alternately start and stop the machine through the latching relay LR, the solenoid valve IV being energized to allow passage of air to the cylinder 59 and de-energized to allow exhaust. Operation of either switch S-2 or S-3 energizing relays R.2, R.3, having respective contacts R2A, R2B, R2C, R2D and R3A, R3B, R3C, starts the motor 130 to rotate the finger 170 at constant speed and at the same time de-energizes relay R4 producing release of valve IV to slow the machine. As the spindle 110 slows the switch arm 120 moves inwards to contact the finger 170 and close switches 175, 176 energizing the valve IV to accelerate the machine until the finger 170 leaves the arm 120 and the switches 175, 176 open again. The machine is thus driven at the speed of the finger 170 until the arm 120 makes contact with either 162 or 163 (according to the closure of S2 or S3) when the valve 2V is energized to rapidly brake the machine in that predetermined position. The incorporation of contacts R2D in the line from contact 163 ensures that thread breakage takes precedence over full cop conditions. In a modification as applied to a sewing machine, the switches S-2, S-3 are combined as a single-pole double throw switch to provide for needle-up and needle-down stopping when the switch S-1 is used.